This invention relates to a method and an apparatus for detecting and recording the number of phenomena occurring during succeeding recording periods, onto a recording tape. The problem of detecting and recording the number of particular phenomena has to be solved in many applications, for instance when checking or supervising a continuous production of various products, when counting traffic and in many further cases of statistic evaluation of events and phenomena.
Various apparatus for detecting and recording phenomena are known wherein graphs are recorded, the length of each graph corresponding to the number of phenomena detected by one detecting unit during a predetermined measuring period or while testing a predetermined length of a product, for instance an enamelled wire. Such graphs are preferably recorded on a recording tape in a direction transversal to the advancing direction of the recording tape which is stepwise advanced at the end of each recording period. Since the phenomena recorded usually occur at random, the length of the individual graphs recorded on the tape varies, that is, the number of phenomena recorded during each test period is subject to changes. However, if no phenomena are recorded during a number of periods, it is impossible to conclude clearly from this fact, whether no phenomena have occurred or whether the detecting and/or recording apparatus is defectuous.